The present invention relates generally to an injection molding machine, and more particularly to a method and a device for clamping electromagnetically the molds of the injection molding machine.
The mold clamping technique of the conventional injection molding machine involves an oil pressure cylinder or servo motor, which serves as a power element to carry out the process of closing or opening the mold in conjunction with a toggle mechanism and a tie bar, which are used for enlarging and transmitting the mold locking force. The conventional mold clamping unit is rather complicated in construction and is relatively high in relevant geometric precision dependency. In addition, the mold locking force of the conventional mold clamping unit is unevenly distributed, thereby resulting in poor mold-locking performance. Furthermore, the tie bar is susceptible to fatigue. In light of the deficiencies described above, the conventional injection molding machine can not be miniaturized and refined. It must be noted here that the miniaturization of the injection molding machine is the industrial trend.
The U.S. Pat. No. 5,352,394 discloses injection molding method and apparatus with magnetic mold clamping. The mold board has a front segment, which is displaced by means of a half hold plate which is mounted on a guide threaded rod and is actuated by a servo motor. As other half mold plate is closed, the electromagnetic force is acted as the force establishing source of the mold locking force. In other words, the current output is brought about into the electromagnetic coil of the half mold plate, so as to generate the magnetic force. In the meantime, the molding tool is caused to generate the mold locking force. Upon completion of injection molding, the current supply is interrupted so that the mold locking force is dissipated. The servo motor actuates in reverse the guide threaded rod to open the molding tool. The servo motor is used as a power source to attain the displacement of the mold board so as to close or open the molding tool. The electromagnetic device is another power source device for generating the mold locking force. This structure solves only part of the problems of the conventional injection molding machine and involves the use of two power sources consisting of the servo motor, the guide threaded rod, and the guide threaded rod protecting device, which are expensive component parts. In addition to the high cost, the motion control is complicated.
It is the primary objective of the present invention to provide a method and a device for clamping electromagnetically the mold of an injection molding machine. The present invention makes use of the electromagnetic force as a power source to bring about the mold board displacement and the mold locking force.
It is another objective of the present invention to provide a method and a device for clamping electromagnetically the mold of an injection molding machine. The motion control of the present invention is precise and easy.
The present invention comprises a stand, a fixed board mounted on the stand, a guiding mechanism mounted on the stand, a movable board mounted slidably on the guiding mechanism, one set of molding tool having a male mold and a female mold, which are respectively mounted on the fixed board and the movable board. The mold opening action, the mold closing action, and the mold locking action are brought about by the sliding motion of the movable board in relation to the fixed board. The movable board and the fixed board are internally provided with a power source device which has a magnetic force generating mechanism. At least the magnetic force direction and the magnetic force magnitude of one side are adjustable such that an attractive force and a repulsive force are effected between the movable board and the fixed board. The attractive force serves as the mold closing force and the mold locking force between the mold boards. The repulsive force serves as the mold opening force.